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Model Steam Engine Plans

Hot Air / Vacuum / Stirling Engines

Hot air engines (sometimes known as vacuum engines) operate on the two stroke cycle and rely on an external heat source to drive the power piston, but not in a conventional manner as they actually suck the power piston along its stroke.

Vacuum engines use heated air (or sometimes steam at very low pressure), as is about to ( as shown here in the picture) with the flywheel rotating, entering a cylinder until it is full when the cylinder is sealed by a simple valve so that the metalwork chills the air (or steam) creating a partial vacuum, that way sucking the piston to the top of the cylinder with a power stroke. The flywheel providing the momentum for the next induction of the heated gases.

The candle engine listed below is a good example of our vacuum engine plans and complete versions can be found in our General Model Steam Engine Kits listing.

Stirling engines (also shown in the above link, sometimes known as hot air engines) on the other hand have a sealed system where one simple type has a large cylinder where a very loose fitting displacer piston is encapsulated, sliding up and down the cylinder and displacing the trapped air from one side of the piston to the other.

stirling engineOn one side of this piston the cylinder is heated to warm the air, while the other side is cooled to chill it.

Because of the displacement of the air from the cold end to the warm end as the piston travels along its stroke, there is a small amount of pressure exerted on a much smaller piston (the power piston shown below the crank in this drawing) with a flywheel attached causing a power stroke. At the other end of the large piston's stroke the air is chilled, meaning the small piston is now sucked back towards the main pistons chamber, causing a second power stroke

To make these engines work the pistons need to be offset from each other at 90 degrees and because of the small change in temperature between hot and cold, these engines are not powerful and in the model scales we work with can really only provide the power needed for fans and the likes.

Our stirling engine pdf plans and diy files show you how to build a stirling engine at home whether its a new stirling engine diy project, a desk-top working model stirling engine or one you've been promising yourself for years.

Check out the links on the left for more ready-made options...

Available plans
Poppin Vacuum  Engine                             Free
Candle Engine                                           Free
Stirling Engine                                            Free
Hot Air Engine                                           Free

Air Cooled Hot Air Engine
Vacuum Motor   -                  German Script but simple design to follow
Fire Eater   -                          Easy build
Stirling Engine Blueprint   -     German Script
Popular Mechanics Boiler
Vacuum Motor
Water Motor
Plus other engines 
Only  2.67